Spark plugs of this nature have long been known from DE 197 05 372 C2 and U.S. Pat. No. 5,408,961 A. Spark plugs of this type have also long been manufactured in quantity and used in stationary, gas-powered internal combustion engines in which each combustion chamber has a prechamber into which the front end of such a spark plug projects. The prior art spark plugs have relatively thin web sections at their ground electrodes with relatively large scavenging ports located between them, by means of which scavenging ports an annular space located in the body of the spark plug stands in connection with the environment outside the spark plug, and which scavenging ports permit good scavenging of the annular space and the spark gap with the combustion gas/fuel mixture flowing into the prechamber of the internal combustion engine when the spark plug is operated. Spark plugs of this type permit good and reliable ignition of the combustion gas/air mixture, even when this is a “lean mixture” in which the amount of air actually present is greater than the amount of air stoichiometrically required for complete combustion of the combustion gas.